Bags and other types of luggage are used to carry items and to store and protect possessions during travel. There are innumerable styles and sizes of bags and other forms of hand luggage available on the market, each one suited for a slightly different purpose. In selecting a bag for a particular task, two problems arise. First, it can be difficult to decide what size of bag to use. If one chooses too small a bag for a particular task, there is a chance that one will not be able to fit all that he or she would have liked into that bag. Choosing a bigger bag makes it more likely that one will be able to accommodate all of the items that he or she wishes to carry; however, large bags can be cumbersome and difficult to carry.
Second, it is generally desirable to choose a type of bag that suits the items that are to be carried. For example, duffel bags, which are cylindrical or rectilinear cloth bags with hand straps, are often used to carry clothes and possessions, but they may not be the most appropriate bag for smaller items. Moreover, the elongate cylindrical or rectilinear shape of the duffel bag may make it overly bulky and cumbersome in some situations.
One partial solution to the problems noted above is to use an expandable bag, and a number of expandable bags are known. For example, U.S. Pat. No. 4,773,515 to Kotkins, Jr. discloses a duffel bag with a bellows-like expanding joint on each end. A similar bellows-type expansion is found in the typical valise, exemplified by U.S. Pat. No. 5,211,716 to Tobias. However, in each of these two cases, the configuration of the bag does not change; it is merely capable of expanding somewhat in size.
By contrast, commonly-assigned U.S. Pat. No. 7,500,547 discloses a piece of hard-sided wheeled luggage in which the cover of the piece of luggage acts as an expansion panel, allowing the volume of the luggage to increase in order to accommodate additional articles. The luggage also includes features that allow it to collapse and fold when not in use, thus reducing the amount of space needed to store it. However, this type of expandable collapsing luggage is not intended to store articles while in the collapsed and folded configuration.